HP StorageWorks 12000 - Virtual Library System EVA Gateway Manual page 202

all objects in the primary storage pools. Data is stored in a copy storage pool when you back up
active and inactive data in a primary storage pool. A copy storage pool uses only sequential-access
storage (e.g., a tape or FILE device class).
The following TSM copy methods will deduplicate successfully in the VLS:
• Using "simultaneous writes" to a primary storage pool and one or more copy storage pools.
For example, you could backup to a disk pool and simultaneously copy to one or more VLS
devices, or you could backup to a VLS and simultaneously copy to another VLS.
• Copying data from a disk storage pool to a VLS. This requires the disk pool size to be at least
equal to your largest nightly backup; see "Disk pools" above.
NOTE:
Deduplication does not currently support backing up to one VLS and then copying from that VLS
to another VLS. Deduplication is performed on the first VLS but not the second.
• Virtual volumes: TSM allows one TSM server to store its data on another TSM server. The TSM
server that sends the data to be stored on the other server is the source server, and the server that
stores the received data is the target server. With virtual volumes, the source server treats the target
server like a tape library, and the target server treats the source server as a special type of client
node.
Deduplication does not support TSM virtual volumes.
• Reclamation: Limit the number of concurrent reclamation jobs per pool to one. TSM reclamation
is the process of reclaiming space on sequential access storage pool volumes. Space becomes
reclaimable when files expire or are deleted (as identified by expiration processing). Reclamation
processing consolidates the remaining active data from multiple sequential access volumes onto
fewer volumes.
Reclaimed cartridges, those which were the source of reclaimed data, are essentially untouched
by reclamation but are made available (scratched) for later reuse. The TSM reclaimed data is
copied to a new cartridge, but none of this data will be deduplicated. The TSM reclaimed data
is shown in the user interface as "Disabled, Unsupported and Overhead Data" on the System
Capacity screen (System > Chassis > Deduplication > System Capacity).
The TSM default reclamation threshold should be set to at least 90% or higher. If you run reclam-
ation, reclaimed backups are expanded and subsequent backups are not deduplicated against
them. For example, with the default reclamation threshold at 90%, 10% of the data will not be
deduplicated.
You should run reclamation outside of the backup window because it reduces processing bandwidth.
The reclamation process is very device-intensive and requires at least two available drives in the
library (to read and to write). You must increase the amount of available capacity for the retention
period of the reclaimed backup data.
• Co-location: Co-location minimizes the number of tape volumes that need to be written to and is
activated on the storage pool level. If the storage pool that you send backups to is co-located,
then backups are co-located as specified by that storage pool. The greatest degree of co-location
is filespace co-location, followed by client co-location, then co-location groups. The more data
you collocate, the fewer tape mounts are required during restores. The downside is that you will
significantly increase the amount of tapes you use.
Deduplication does not support co-location because this feature is unnecessary when using a disk-
based backup solution.
• NDMP backup: Deduplication does not currently support LAN-free NDMP with TSM. This means
you can only backup an NDMP filer over the LAN to the VLS.
202 Virtual Library Systems